SOUTH LAKE TAHOE — Scuba-diving scientists and a battalion of government officials launched an aquatic assault Friday on alien invaders threatening to slime one of the world's most pristine lakes.

In a $1.4 million experiment led by researchers from the University of California, Davis, and the University of Nevada, the team set out to smother millions of the slovenly freeloaders – non-native Asian clams that spew algae-causing concentrates into Lake Tahoe.

"You have to think of these clams as sucking factories," said Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center. "They suck in the water and they filter out the algae. Their excretions are highly concentrated packages of nutrients."

The dime-sized clams – first discovered in 2002 – are a serious menace to the lake ecology and a threat to its renowned clarity, government scientists and water quality groups say.